Certain firefighting vehicles can be equipped with a foam addition system that can add a foam concentrate to a water stream and thereby discharge a foam/water mixture in order to suppress or prevent a fire. Generally, it is desirable to test the accuracy of a firefighting vehicle's foam addition system to ensure that the correct amount of foam is being added to the water stream so that the foam/water mixture being discharged has the proper amount of foam. Certain current methods used to test the accuracy of a foam addition system can involve the actual discharge of a foam/water mixture into the environment. However, the discharge of certain fire retardant foam compositions into the environment may have negative environmental effects. Therefore, there is a need for systems and methods that can test the accuracy of a foam addition system without actually discharging any foam into the environment during the testing procedure.